The Kansas City-based tax preparer said Wednesday that more than 90 percent of affected clients have received their refunds or a notice of a possible refund date.

The update came after the IRS announced March 12 that software problems affecting about 660,000 tax returns would delay refunds by as long as six weeks. The IRS later announced that the processing delays would last closer to two to four weeks. The agency had nothing new to add Wednesday.

The glitch affected people claiming education tax credits who filed returns between Feb. 14 and Feb. 22. Besides H&R Block, a limited number of other software companies also had problems, but the IRS hasn't named them.